When strings are compared using String.Compare, comparison results may differ depending on the machine's locale. The canonical example is the Turkish where there is a lowercase dotless "ı" with the corresponding uppercase "I", and a lowercase "i" with an uppercase "İ" with the dot. As a result, your code may return different results on machines with different culture settings.

To resolve this problem, ReSharper suggests adding the culture-invariant StringComparison.Ordinal explicitly to the method call.